JP2005134526A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can prevent contamination of a transfer device when operation is stopped due to abnormality by a simple configuration. <P>SOLUTION: The image forming apparatus has an image carrier 14 which carries a toner image and rotates and a transfer roller 12 which rotates and constitutes a transfer section together with the image carrier 14, and can be switched between a normal state when the image carrier 14 is in contact with the transfer roller 12 and a separation state when these elements are apart from each other. The apparatus has a spacer member 20 which prevents a contact state between the image carrier 14 and the transfer roller 12 in a normal state, and has a spring 24 which allows the top end 22 of the spacer member 20 to protrude into the contact area of the image carrier 14 and the transfer roller 12. The top end 22 is rejected from between the image carrier 14 and the transfer roller 12 when the image carrier 14 or the transfer roller 12 rotates in a normal state. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer. More specifically, the present invention relates to an image forming apparatus in which an image carrier and a transfer member can be separated from each other.

  2. Description of the Related Art Conventionally, in an image forming apparatus that forms an image with toner, a toner image formed on an image carrier is transferred onto a sheet by a transfer device and fixed by a fixing device to form an image. However, when an emergency stop of the apparatus is performed due to an abnormality such as a paper jam, the toner that has not been transferred may remain on the image carrier. If the apparatus is restarted in this state, the toner remaining on the image carrier may adhere to the transfer member during warm-up. In this case, there is a problem that the paper is stained on the back side during subsequent image formation.

On the other hand, an image forming apparatus has been proposed in which a secondary transfer roller is separated from an intermediate transfer belt by a cam when an abnormality such as a paper jam occurs (see, for example, Patent Document 1). According to this image forming apparatus, when an abnormality occurs, the secondary transfer roller does not come into contact with the intermediate transfer belt for a while, and the secondary transfer roller is contaminated by the toner remaining on the intermediate transfer belt. Is prevented.
Alternatively, an image forming apparatus in which both ends of the transfer roller are supported by solenoids and the transfer roller is separated from the photosensitive member by the solenoid in the event of an abnormality has been proposed (for example, see Patent Document 2).
JP 2001-92271 A (page 4-5, FIG. 3) JP-A-8-62994 (page 4-5)

  However, all of the above-described conventional image forming apparatuses move the transfer device away from the image carrier by the power of a cam or solenoid. Therefore, a drive source, a control means, etc. for press-contacting or separating as needed are needed. For this reason, there is a problem that the apparatus becomes complicated and large, and further, the cost is increased.

  The present invention has been made to solve the problems of the conventional image forming apparatus described above. That is, an object of the present invention is to provide an image forming apparatus that can prevent the transfer device from being soiled at the time of abnormal stop with a simple configuration.

  An image forming apparatus according to the present invention, which has been made for the purpose of solving this problem, includes an image carrier that carries and rotates a toner image, and a transfer member that forms a transfer portion together with the image carrier and rotates. An image forming apparatus capable of switching between a normal state in which the body and the transfer member are in contact with each other and a separated state in which these members are separated from each other, and forming an image on the recording medium by passing the recording medium through the transfer portion in the normal state A contact preventing member for preventing contact between the image bearing member and the transfer member in a normal state, and a rushing means for projecting the tip of the contact preventing member into a contact portion between the image bearing member and the transfer member; The contact prevention member is removed from between the image carrier and the transfer member when the image carrier or the transfer member rotates in a normal state.

  In the image forming apparatus of the present invention, the image carrier and the transfer member can be switched between contact and separation. Here, according to the present invention, since the contact prevention member and the rushing means are further provided, the tip of the contact prevention member is rushed into the contact point between the image carrier and the transfer member by the rushing means. Therefore, the contact preventing member prevents contact between the image carrier and the transfer member in a normal state. For example, when an abnormality such as a jam is processed, the image carrier and the transfer member are once separated from each other. If a contact prevention member is inserted at that time, the image carrier and the transfer member are in a normal state immediately after the abnormality processing. Contact with is prevented. Therefore, even when toner remains on the image carrier at the time of abnormal stop, there is no possibility of adhering to the transfer member. Further, since the contact preventing member is removed from between them by the rotation of the image carrier or the transfer member, the image carrier and the transfer member are returned to the normal contact state by driving during warm-up. In general, the image carrier is cleaned during this time. That is, since no special moving means for moving the transfer member after the abnormal process is required, the image forming apparatus has a simple configuration and can prevent the transfer device from being soiled when abnormally stopped.

Further, in the present invention, in the normal state, the contact prevention member is in contact with the shorter end surface of the image carrier and the transfer member, and in the separated state, the contact prevention member is separated from the image carrier by the urging force of the entry means. When it enters between the transfer member and returns to the normal state from the separated state, the contact prevention member prevents contact between the image carrier and the transfer member, and the contact is achieved by rotating the image carrier or the transfer member. It is desirable that the prevention member is excluded from between the image carrier and the transfer member.
In this way, the contact preventing member is inserted between the image carrier and the transfer member in the normal state without interfering with the contact between the image carrier and the transfer member. By returning to the normal state as it is, contact between the image carrier and the transfer member is prevented, so that toner remaining on the image carrier does not adhere to the transfer member. Further, since the image carrier or the transfer member is rotated during warm-up or the like, the contact prevention member is eliminated during that time, and thereafter, the image carrier and the transfer member are brought into a normal contact state.

Further, according to the present invention, the contact prevention member is formed with an inclined section having a thickness or a diameter that is smaller toward the tip, and the contact prevention member is caused to enter the contact portion between the image carrier and the transfer member by the entry means. In this state, it is desirable that at least one end of the image carrier and the transfer member is located on the inclined section of the contact preventing member.
In this way, the contact preventing member is excluded from the space due to the frictional force applied to the inclined section by the rotation of the image carrier or the transfer member.

Furthermore, the present invention has a support shaft that is located on the rear side of the contact prevention member and supports the contact prevention member so as to be movable in the entry direction, and a pin provided on the support shaft. It is desirable to form a slit that regulates the moving range of the direction.
In this way, the entry direction of the contact preventing member in the separated state is regulated by the support shaft, and the movement range of the entry is regulated by the pin and the slit.

Furthermore, in the present invention, it is desirable to have an open / close door that is a part of the exterior body and that can be opened and closed, and that holds the transfer member, and that the normal state and the separated state can be switched by opening and closing the open / close door.
In general, when an abnormality occurs, the user opens the door and performs an abnormality process. At this time, the transfer member held by the door is moved together with the door. That is, when an abnormality occurs, the contact prevention member can be rushed in between because it is in a separated state for the treatment.

Furthermore, in the present invention, the contact prevention member may be a fan-shaped member that rotates around an axis.
In this way, the fan-shaped member can be inserted between the image carrier and the transfer member, thereby functioning as a contact preventing member. Further, if the fan-shaped member is rotated around the axis, a portion having no member reaches between the image carrier and the transfer member, and the state is eliminated.

  According to the image forming apparatus of the present invention, it is possible to prevent the transfer device from being soiled at the time of an abnormal stop with a simple configuration.

"First form"
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a relatively large image forming apparatus such as a large printer or a copying machine.

  The image forming apparatus 1 of the present embodiment has a door 11 that can be opened and closed on a side surface as schematically shown in FIG. The transfer roller 12 is attached to the door 11 and is moved together with the door 11 by opening and closing the door 11. In other words, in the image forming apparatus 1, the transfer roller 12 can be separated from the image forming unit 13 by a door opening / closing operation by a user. The image forming unit 13 is a general unit in which a cleaner device 15, a charging device 16, an exposure device 17, and a developing device 18 are arranged around an image carrier 14. A sheet 19 is conveyed between the image carrier 14 and the transfer roller 12.

  When the image forming apparatus 1 is viewed from above in FIG. 1, spacer members 20 and 20 are provided at both ends of the image carrier 14 and the transfer roller 12, respectively, as shown in FIG. Further, the image carrier 14 is formed slightly longer in the axial direction than the transfer roller 12. In addition, pitch rings 21 and 21 are attached to both ends of the transfer roller 12. The pitch rings 21 and 21 are for defining the amount of biting when the transfer roller 12 formed by, for example, a foam roller or an elastic roller is pressed against the image carrier 14. And the front-end | tip part of the spacer members 20 and 20 is contact | abutted to the pitch rings 21 and 21 of both ends, respectively. In other words, in this state, the end portions of the spacer members 20 and 20 are in contact with the shorter end surface of the image carrier 14 and the transfer roller 12.

  As shown in FIGS. 2 and 3, each spacer member 20 has a tip 22, a support shaft 23, a spring 24, and a pin 25. The front end portion 22 is a substantially wedge-shaped hollow member having an inclined section 22a, and a support shaft 23 is inserted into the hollow portion. A slit 26 having a predetermined length is provided in the axial direction of the support shaft 23 on the outer surface of the tip 22. One end of the support shaft 23 is inserted into the distal end portion 22, and the other end is fixed to the image forming unit 13 or the main body case. The spring 24 is provided along the support shaft 23 and urges the tip 22 toward the tip of the support shaft 23. The pin 25 is attached to the tip of the support shaft 23 and is located in the slit 26 of the tip 22. As a result, as shown in FIGS. 4A and 4B, the distal end portion 22 of the spacer member 20 can be moved by a predetermined distance in the axial direction of the support shaft 23 by extending and contracting the spring 24. In FIG. 3, the shape is shown upside down from FIG. 2 for easy understanding of the shape.

  Further, as shown in FIG. 2, the spacer member 20 is mounted with the inclined surface 22a of the tip end portion 22 facing the transfer roller 12 and the plane side facing the image carrier 14. . The plane side is disposed at a position in contact with the outer peripheral surface of the image carrier 14. In the state shown in FIG. 2, the spring 24 is contracted, and the tip 22 of the spacer member 20 is pressed against the pitch ring 21 by its restoring force.

  When an image is formed by the image forming apparatus 1, the image carrier 14 is rotated in the direction of the arrow in FIG. Then, following the rotation, it is cleaned by the cleaner device 15, charged by the charging device 16, an electrostatic latent image is formed by the exposure device 17, and developed with toner by the developing device 18. In FIG. 1, the toner is schematically shown by black circles. Then, the toner is transferred by the transfer roller 12 to the sheet 19 supplied between the image carrier 14 and the transfer roller 12.

  Here, if an abnormality such as a paper jam occurs during the image formation, the image forming operation is interrupted. Then, the user opens the door 11 to take out the jammed paper. Then, as indicated by a two-dot chain line in FIG. 1, the transfer roller 12 is separated from the image carrier 14 and moves to the outside together with the door 11. At this time, since the spacer member 20 does not move together with the door 11, the pressure contact by the pitch ring 21 with respect to the distal end portion 22 of the spacer member 20 is eliminated. For this reason, as shown in FIG. 5, the distal end portion 22 is plunged toward the center by the restoring force of the spring 24. Thereafter, when the jam processing is finished and the user closes the door 11, the transfer roller 12 is returned to the original position together with the door 11. At this time, as shown in FIG. 6, the leading end 22 of the spacer member 20 is sandwiched between the image carrier 14 and the transfer roller 12. That is, the contact between the image carrier 14 and the transfer roller 12 is prevented by the tip 22 of the spacer member 20.

  Here, the range of movement of the front end portion 22 in the central direction is such that the end of the transfer roller 12 is on the slope of the inclined section 22a of the front end portion 22 as shown in FIG. 6 when the door 11 is closed. Up to the contact position. That is, in the state where the spacer member 20 shown in FIG. 4A is the longest, either end of the image carrier 14 and the transfer roller 12 is positioned on the inclined section 22a. Here, since the gap between the image carrier 14 and the transfer roller 12 is not increased more than necessary by contacting the shorter transfer roller 12, an excessive force is applied to the end of the transfer roller 12. There is nothing.

  Further, when the jam processing is completed and the door 11 is closed, the image forming apparatus 1 performs a warm-up operation, and the image carrier 14 and the transfer roller 12 are rotationally driven. Then, since the slope of the inclined section 22a of the front end portion 22 is in contact with the transfer roller 12, the front end portion 22 gradually moves outward from between the image carrier 14 and the transfer roller 12 due to the frictional force generated by rotational driving. Extruded. That is, the spacer member 20 is removed in the both end directions while the spring 24 is contracted, and returned to the arrangement shown in FIG. 2 and stopped. Further, the toner remaining on the image carrier 14 when the jam occurs is collected by the cleaner device 15 during the warm-up operation. Therefore, at the end of the warm-up, the image carrier 14 and the transfer roller 12 are pressed against each other by a normal appropriate pressing force, and a normal image can be formed.

  That is, when the user opens the door 11 for the jam processing, the image carrier 14 and the transfer roller 12 are separated from each other, and the spacer member 20 enters between them. Thereafter, when the door 11 is closed, the spacer member 20 is sandwiched between the image carrier 14 and the transfer roller 12. That is, the image carrier 14 and the transfer roller 12 do not contact immediately after the door 11 is closed. As a result of the warm-up operation of the image forming apparatus 1, the toner remaining on the image carrier 14 is removed by the cleaner device 15 and the spacer member 20 is removed from between the image carrier 14 and the transfer roller 12. . That is, after the image carrier 14 is cleaned, the image carrier 14 and the transfer roller 12 are in a normal pressure contact state. Therefore, the remaining toner does not adhere to the transfer roller 12, and the back side of the paper does not get dirty.

Here, the support shaft 23 of the spacer member 20 is provided along the axial direction of the image carrier 14, but it may be arranged in a direction perpendicular to the axial direction of the image carrier 14, or in an oblique direction. . In this case, if the image carrier 14 and the transfer roller 12 are inserted from the downstream side of the rotation, the image carrier 14 and the transfer roller 12 can be reliably pushed out from between them.
Alternatively, a step may be provided in the inclined section 22a of the tip 22 of the spacer member 20 as shown in FIG. 7 so that the support shaft 23 can be swung. In the example of FIG. 7, by providing a step, the inclined section 22a is further provided with a thin portion 22b and a thick portion 22c. Then, the closer to the tip of the tip portion 22, the narrower the thick portion 22c. By doing so, the spacer member 20 is pushed out along the step due to the rotation of the image carrier 14 and the transfer roller 12, so that the spacer member 20 is more reliably removed.

  As described above in detail, according to the image forming apparatus 1 of the present embodiment, when the apparatus is stopped due to an abnormality such as a jam, the user can open the door 11, so that the image carrier 14, the transfer roller 12, Are separated. At this time, the distal end portion 22 of the spacer member 20 is sandwiched between the image carrier 14 and the transfer roller by the restoring force of the spring 24. Therefore, even if the door is closed, the transfer roller 12 does not immediately contact the image carrier 14, and even if toner remains on the image carrier 14, there is no possibility of adhering to the transfer roller 12. Accordingly, it is possible to prevent the transfer member from being soiled at the time of an abnormal stop with a simple configuration, and it is possible to prevent the back surface of the paper from being soiled.

"Second form"
Hereinafter, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a relatively small image forming apparatus such as a small printer. Since there are many parts in common with the first embodiment, the same reference numerals are given to common members, and descriptions thereof are omitted.

  In the image forming apparatus 2 of the present embodiment, as shown in FIG. 8, the transfer roller 12 is provided below the image forming unit 13. In the image forming unit 13, the image carrier 14, the cleaner device 15, and the charging device 16 are integrated and detachably attached. In addition, the image forming apparatus 2 includes an exposure device 17 and a developing device 18, and the developing device 18 is detachable. In the image forming apparatus 2 configured as described above, when an abnormality such as a jam occurs, the user removes the sheet by removing the image forming unit 13 upward in the drawing.

  In this image forming apparatus 2, spacer members 30 are provided at both ends of the image carrier 14 as shown in FIG. Compared with the spacer member 20 of the first embodiment, the spacer member 30 is attached so that the inclined surface of the inclined section 22a faces the image carrier 14 and the end of the support shaft 23 is swingable.

When an abnormality such as a jam occurs in the image forming apparatus 2, the user removes the image forming unit 13 for the processing. Then, the leading end 22 of the spacer member 30 is plunged into a position between the image carrier 14 and the transfer roller 12 as shown in FIG. When the user returns the image forming unit 13 to the original position after the jam processing, the leading end 22 of the spacer member 30 is sandwiched between the image carrier 14 and the transfer roller 12 as shown in FIG. The image carrier 14 and the transfer roller 12 do not immediately contact each other. At this time, the inclined surface of the inclined section 22 a of the front end portion 22 is brought into contact with the end portion of the image carrier 14.
Here, the inclined surface side of the tip 22 is directed to the side of the image carrier 14 that is a member to be removed at the time of jam processing, so that the plane side of the tip 22 extends along the pitch ring 21 when entering as shown in FIG. Moved. Thereby, even if the support shaft 23 can be swung, the tip 22 is smoothly plunged.

  Thereafter, the image carrier 14 and the transfer roller 12 are rotationally driven, so that the leading end portion 22 of the spacer member 30 is excluded from between them. When the distal end of the distal end portion 22 reaches both ends outside the pitch ring 21, the support shaft 23 is swung downward in the figure to return to the arrangement as shown in FIG. During this time, the toner remaining on the image carrier 14 is cleaned, so that the toner is prevented from adhering to the transfer roller 12. Thereafter, the image carrier 14 and the transfer roller 12 are pressed against each other with a normal pressing force, and normal image formation is possible.

  As described in detail above, according to the image forming apparatus 2 of the present embodiment, as with the image forming apparatus 1 of the first embodiment, the transfer member can be prevented from being soiled at the time of an abnormal stop with a simple configuration. Back dirt can be prevented.

"Third form"
Hereinafter, a third embodiment of the present invention will be described with reference to the accompanying drawings. This form is another form of the tip of the spacer member applicable to either the large image forming apparatus described in the first form or the small image forming apparatus described in the second form. Portions common to the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the spacer member of this embodiment, as shown in FIG. 11, the inclined section 41a has a tip portion 41 having a substantially conical shape. Alternatively, as shown in FIG. 12, the inclined section 42a has a substantially conical shape and has a front end portion 42 on which a spiral screw groove or a step is formed. And these front-end | tip parts 41 and 42 are attached so that rotation around the support shaft 23 is possible. In this way, as with the spacer members 20 and 30, when the distance between the image carrier 14 and the transfer roller 12 becomes large, it is inserted between them to prevent their contact. Further, the image carrier 14 and the transfer roller 12 are rotated and removed by being rotated.

  As described above, the image forming apparatus having the spacer member of the present embodiment can prevent the transfer member from being soiled at the time of abnormal stop with a simple configuration, as in the first and second embodiments. Back dirt can be prevented.

"Fourth form"
Hereinafter, the 4th form which actualized this invention is described in detail, referring an accompanying drawing. This form is another form of the spacer member applicable to either the large image forming apparatus described in the first form or the small image forming apparatus described in the second form. Portions common to the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 13, the spacer member 50 of this embodiment has a wedge-shaped tip portion 51, a support shaft 52, and a weight 53 attached to be rotatable by two rotating portions 54 and 55. Further, a regulating member 56 that regulates the rotation angle of the tip 51 is attached to the support shaft 52. The spacer member 50 is urged toward the position indicated by a two-dot chain line in the drawing by the gravity acting on the weight 53. When the tip 51 is pushed to the right in the drawing, the tip 51 comes into contact with the regulating member 56 and is arranged as shown by a solid line. Therefore, the spacer member 50 is arranged so as to be urged between the image carrier 14 and the transfer roller 12 in the same manner as the spacer members 20 and 30 of the first and second embodiments.

  Even in the image forming apparatus having the spacer member 50 according to the present embodiment, when the image carrier 14 and the transfer roller 12 are separated from each other, the tip 51 is inserted between them by the gravity acting on the weight 53. Then, when the image carrier 14 or the transfer roller 12 is fitted, their contact is prevented. Further, it is eliminated by the rotational drive of the image carrier 14 and the transfer roller 12, and normal image formation becomes possible. Also in this configuration, the tip 51 may be provided with a step as shown in FIG. 7, or may be a conical tip as shown in FIGS.

  As described above, the image forming apparatus having the spacer member 50 according to the present embodiment can prevent the transfer member from being soiled at the time of an abnormal stop with a simple configuration as in the first and second embodiments. Can prevent dirt on the back.

"Fifth form"
Hereinafter, a fifth embodiment of the present invention will be described in detail with reference to the accompanying drawings. This form is another form of the spacer member applicable to either the large image forming apparatus described in the first form or the small image forming apparatus described in the second form. Portions common to the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 14, the spacer member 60 of this embodiment includes a spacer plate 61, a spring 62, and a rotating shaft 63. The spacer plate 61 is a part of a disk-shaped member, ie, a fan-shaped member, and is rotatable around the rotation shaft 63. The spring 62 urges the spacer plate 61 to rotate clockwise in FIG. 14 and may be provided on the rotating shaft 63. The size of the notch of the spacer plate 61 is set to such a size that the image carrier 14 and the transfer roller 12 can contact each other between them. Further, at a rotational position other than the notch, the spacer plate 61 is driven and rotated by being sandwiched between the image carrier 14 and the transfer roller 12 and being driven to rotate.

  In this spacer member 60, the position where the spacer plate 61 contacts the image carrier 14 in the free state of the spring 62 and the end of the notch (the first time the image carrier 14 and the transfer roller 12 both do not contact the spacer plate 61. Is slightly larger than the angle a shown in FIG. 15 and smaller than the angle b. Here, the angle a is an angle formed between the developing device 18 and the transfer roller 12 as viewed from the center of the image carrier 14, and the angle b is the cleaner device 15 and the transfer roller 12 as viewed from the center of the image carrier 14. Is the angle between

  In this way, when the image carrier 14 and the transfer roller 12 are separated for jam processing or the like, the spacer plate 61 is first rotated to the free state position of the spring 62. When the image carrier 14 and the transfer roller 12 are returned to their original positions, the spacer plate 61 is sandwiched between them. When the image carrier 14 and the transfer roller 12 are driven to rotate, the spacer plate 61 is also driven and rotated to the notch position. When the notch position is reached, the image carrier 14 and the transfer roller 12 are brought into contact with each other, and the spacer plate 61 is not further rotated. Since the rotation angle during this period is set as described above, at least the portion of the image carrier 14 to which the toner may be attached is rotated by the developing device 18 until it passes, The transfer roller 12 is contacted.

  As described above, the image forming apparatus having the spacer member 60 of the present embodiment can prevent the transfer member from being soiled at the time of an abnormal stop with a simple configuration, as in the first and second embodiments. Can prevent dirt on the back.

Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in each of the above embodiments, the shape of the tip of each spacer member is not limited to these, and it is sufficient that the thickness decreases toward the tip or the diameter decreases.
Further, for example, in each of the above-described embodiments, it has been described that the spacer member is inserted between the image carrier 14 and the transfer roller 12. However, the present invention is not limited to this, and can be applied to any transfer location. For example, the present invention can be similarly applied to a transfer location between the image carrier and the sheet conveying belt, a transfer location between the intermediate transfer belt and the secondary transfer roller, and the like.
Further, for example, the schematic configurations of the image forming apparatuses shown in the first and second embodiments are merely examples, and the present invention is not limited to these. The present invention can be applied to any image forming apparatus as long as the image carrier and the transfer roller are once separated at the time of jam processing or the like.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment. It is explanatory drawing which shows a spacer member. It is a perspective view which shows a spacer member. It is sectional drawing which shows a spacer member. It is explanatory drawing which shows the movement of a spacer member. It is explanatory drawing which shows the movement of a spacer member. It is a perspective view which shows the front-end | tip part of a spacer member. It is sectional drawing which shows schematic structure of the image forming apparatus which concerns on a 2nd form. It is explanatory drawing which shows a spacer member. It is explanatory drawing which shows the movement of a spacer member. It is a perspective view which shows the front-end | tip part of the spacer member which concerns on a 3rd form. It is a perspective view which shows the front-end | tip part of the spacer member which concerns on a 3rd form. It is explanatory drawing which shows the spacer member which concerns on a 4th form. It is a perspective view which shows the spacer member which concerns on a 5th form. It is explanatory drawing which shows the rotation angle of the spacer member which concerns on a 5th form.

Explanation of symbols

1, 2 Image forming device 12 Transfer roller (transfer member)
14 Image carrier 22, 41, 42, 51 Tip (contact prevention member)
22a, 41a, 42a Inclined section 23 Support shaft 24, 62 Spring (entry means)
25 pin 26 slit 53 weight (rushing means)
61 Spacer plate (contact prevention member)

Claims (6)

A normal state in which the image carrier and the transfer member are in contact with each other, and an image carrier that carries the toner image and rotates, and a transfer member that constitutes a transfer portion together with the image carrier and rotates. In an image forming apparatus which can be switched between a separated state and a normal state in which an image is formed on a recording medium by passing the recording medium through a transfer position.
A contact preventing member for preventing contact between the image carrier and the transfer member in a normal state;
Rushing means for piercing the tip of the contact preventing member into the contact portion between the image carrier and the transfer member;
The image forming apparatus according to claim 1, wherein the contact preventing member is removed from between the image carrier and the transfer member when the image carrier or the transfer member rotates in a normal state. The image forming apparatus according to claim 1,
In a normal state, the contact prevention member is in contact with the shorter end surface of the image carrier and the transfer member,
In the separated state, the contact preventing member rushes between the image carrier and the transfer member by the urging force of the rushing means,
When returning from the separated state to the normal state, the contact prevention member prevents contact between the image carrier and the transfer member,
An image forming apparatus, wherein the contact preventing member is removed from between the image carrier and the transfer member by rotating the image carrier or the transfer member. The image forming apparatus according to claim 1, wherein:
The contact prevention member is formed with an inclined section having a smaller thickness or diameter closer to the tip.
In a state where the contact preventing member is caused to enter the contact portion between the image carrier and the transfer member by the entry means, at least one end portion of the image carrier and the transfer member is the contact prevention member. An image forming apparatus, wherein the image forming apparatus is located on an inclined section. The image forming apparatus according to claim 3,
A support shaft that is located on the rear side of the contact prevention member and supports the contact prevention member so as to be movable in the entry direction;
A pin provided on the support shaft;
An image forming apparatus, wherein the contact preventing member is formed with a slit for regulating a moving range in a rush direction together with the pin. In the image forming apparatus according to any one of claims 1 to 4,
An opening / closing door that is a part of the exterior body and can be opened and closed, and holds the transfer member;
An image forming apparatus, wherein a normal state and a separated state are switched by opening and closing the door. The image forming apparatus according to claim 1, wherein:
The image forming apparatus according to claim 1, wherein the contact preventing member is a fan-shaped member that rotates about an axis.

Images